Use USB OTG in host mode

[frm]

Hi,
Can I change the configuration of the microUSB OTG in my OLinuxino A64 to use it in "host mode" instead of "pheripheral mode" ?

I only found this post https://www.olimex.com/forum/index.php?topic=4990.0 which mentions a FEX file somewhere... and it's dated 2016

Thanks

[LubOlimex]

Hardware-wise it is possible since there is USB0-ID wire/signal. So the port supports both device and host mode, it is real OTG.

Software-wise I don't think the Olimage image supports it, so some changes to the image are required.

The info you found applies to older sunxi-based images, that used fex files, it does not apply to the Olimage Linux which uses mainline. You'd have to edit dts/dtb. Refer to the Olimage guide, there is info on how to change dts/dtb or kernel:

https://raw.githubusercontent.com/OLIMEX/OLINUXINO/master/DOCUMENTS/OLIMAGE/Olimage-guide.pdf

[frm]

Software-wise I don't think the Olimage image supports it, so some changes to the image are required.

This is really a pity. Right now I don't want to go through the lengthy process of rebuilding the kernel and the image myself, so I'll just use a basic USB hub to expand the single USB host port. It makes the whole setup much less compact thought :-(

Thanks

[winfried]

Since also need this for my A64 Rev.E , to connect a keyboard on the mini USB-OTG, USB-A already used by another device:

You'd have to edit dts/dtb. Refer to the Olimage guide, there is info on how to change dts/dtb or kernel:

Installed the crosscompiler and can make dtb. So what I have to edit ?

found in arch/arm64/boot/dts/allwinner/sun50i-a64-olinuxino-1G.dts

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&usb_otg {
        dr_mode = "otg";
        status = "okay";
};

I cannot figure out what to change, or what mode to define and where to find the documentation for this.

Any hint ?

mfg winfried

[winfried]

First report:

- Measured that the USB-OTG Pin is set to GND with OTG cable and made the mouse test. So the OTG functionality seems to be broken.

Changed the devicetree:

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&usb_otg {
        dr_mode = "host"; /* set to host from otg */
        status = "okay";
};

Result:
3 seconds after boot mouse is detected and is powered  and after 33 second usb0-vbus is disabled and mouse is disconnected. So there is somewhere a timeout or the like.

Suspected the autosuspend, disabling, but still something in the system switches of the usb0-vbus, so disabled "USB Autosuspend" in Linux (Runtime Power Management).

in /boot/uEnv.txt put the line

Code Select Expand

optargs=usbcore.autosuspend=-1but this did not help.

What also is suspect is that there is a

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/sys/devices/platform/usb1-vbusbut no

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/sys/devices/platform/usb0-vbus
So I stop for today, any hint is welcome

[LubOlimex]

The problem is the powering. I used AI to analyze what can be done and got it working if I force it in host mode but that is dangerous (in case you want device mode at some point). I will see if I can get it working properly in dual mode and will give you some instructions.

[winfried]

Thanks, will wait for your result.

Just for info:
Also tried to disable the <&reg_drivevbus> for the _vbus-supply ind dts, but didnt help.

Code Select Expand

&usbphy {
status = "okay";
usb0_id_det-gpios = <&pio 7 9 GPIO_ACTIVE_HIGH>; /* PH9 */
usb0_vbus_det-gpios = <&pio 7 6 GPIO_ACTIVE_HIGH>; /* PH6 */
usb0_vbus-supply = <>; /* Remove or disable ID pin detection if it forces power-off */
usb1_vbus-supply = <&reg_usb1_vbus>;
};

mfg winfried